To Flutter, To Suddenly Change
intransitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. While the kanji means flip, the verb vocab version is to billow or to flutter, as in some kind of material (maybe a dress or a flag) billowing or fluttering in the wind. It can also mean to suddenly change your mind, or your attitude, etc.
For something to billow and to flutter, you'll need to ask the here guy (ひるがえ) - that's guy who's here right now - to open the window and let in the breeze.
I know her skirt billowed in the wind, but rendering how he felt at the time is too difficult.